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Information Classification: ProprietaryInformation Classification: Proprietary
Technical Requirements of Grid Connection of Renewable Energy System
May 2019
Remarks:This material/event is funded by the Professional Services Advancement Support Scheme of the Government of the Hong Kong Special Administrative Region.Any opinions, findings, conclusions or recommendations expressed in this material/any event organised under this project do not reflect the views of the Government of the Hong Kong Special Administrative Region or the Vetting Committee of the Professional Services Advancement Support Scheme.
Information Classification: Proprietary
Contents
Page 2
o Renewable Energy System (RES)
• System Overview
• Grid Connection Overview
o Grid Connection of RES
• Considerations & Constraints
• Example of Grid Connection
• Application Process
o Customer’s Technical Considerations of Grid
Connection of RES
o Feed-in Tariff Scheme – Metering Requirements
Information Classification: Proprietary
RES - System Overview
Page 3
Type of RES
• Solar energy• Wind energy
• Hydro energy• Geothermal energy
• Tidal energy• Biomass energy
• Energy from waste
Eligible to join Feed-in Tariff Scheme
Information Classification: Proprietary
RES - System Overview
Page 4
Characteristics of electricity generated from RES:➢ Intermittent
➢ Unstable & irregular
Equivalent output level = 9%
Information Classification: Proprietary
RES - Grid Connection Overview
Page 5
Standalone RES:
➢ Supply a dedicated load
➢ Totally isolated to utility’s grid
➢ No Standby supply from utility
Grid connected RES:
➢ Standby supply from utility
▪ Change-over Design Connection
▪ Parallel Design Connection
Eligible to join Feed-in Tariff Scheme
Information Classification: Proprietary
Grid Connection of RES - Considerations & Constraints
Page 6
o Reserve sufficient supply capacity to back up RES
o Capability of existing supply network for RES exporting power
Example: Voltage rise due to excessive power exporting from RES to utility’s distribution grid at network remote end
• Violation of upper voltage limit stipulated by the Supply Rules
• Voltage rise limit could be a concern for limiting the capacity of RES grid connection
Information Classification: Proprietary
Grid Connection of RES - Example
Page 7
DC Panel
Utility Supply
Customer
load
Switch with OCEF protectionRemarks: Utility will
install Meter for RES
4-P lockableIsolator
Solar Panel
LV board
Inverter with built-in Isolation Transformer
When RES is connected to grid, reliable supply from grid will be available to back up insufficient generation of RES
Information Classification: Proprietary
Grid Connection of RES - Application Process
Page 8
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 9
• Cap. 406 of Electricity Ordinance
• EMSD:• Technical Guidelines on Grid
Connection of Renewable Energy Power Systems (2016 Edition)
• Code of Practice for the Electricity (Wiring) Regulations (2015 Edition)
o Related Statutory Electricity Ordinances & Guidelines
EMSD:Guidance Notes for Solar Photovoltaic (PV) System
Installation
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 10
o Related Statutory Electricity Ordinances & Guidelines
CLP:• Supply Rules
• Guide to Supply and Metering Arrangement on Customer’s Internal Distribution System
• Feed-in Tariff Scheme Standard Metering Requirements
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 11
o RES Connected to Grid
DC
Panel
CLP Supply
Switch with
OCEF
protection
Inverter FiT Meter
board
LV board
CLP Revenue
Meter board
Isolation
Transformer
Solar Panel
Cable
Circuit
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 12
o Safety Considerations• Operation Procedures
• Lockable Isolation Switch
Lockable Isolation Switch
Operation Procedures
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 13
o Safety Considerations• Warning Labels
DC Warning Label
AC Dual-Source Warning Label
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 14
o Anti-Islanding• Loss-Of-Main Supply Test
RES output voltage
RES output current
Open the Lockable Isolation Switch (Isolation Point)
Inverter output V drops to zero within 200ms after the circuit is opened
200ms
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 15
o Equipment Protection• Fault Current Protection
• 2-P or 4-P Circuit Breaker or Isolator
• Fault Current Contributed by RES
Fault Current Protection 4-P Circuit Breaker
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 16
o Power Quality• Voltage
• Frequency
• Power Factor
• Total Harmonic Distortion (Current)
• Restrict DC content flowing into the AC side
(Isolation transformer shall be used at the inverter output side to limit the DC)
Voltage Total Harmonic Distortion Isolation transformer
Information Classification: Proprietary
Customer’s Technical Considerations of Grid Connection of RES
Page 17
o Revenue Meter & FiT Meter Location
CLP:
• Feed-in Tariff Scheme Standard Metering Requirements
Information Classification: Proprietary
Feed-in Tariff Scheme – Metering Requirements
Page 18
Inverter with built-in
Isolation transformer
LV board
Solar Panel
DC
Panel
*Post-
Meter
lockable
Isolator
CLP Supply
CLP Revenue
Meter board
FiT Meter
boardFiT Meter board
RES
• Record the amount of electricity used by the Customer
• Equipped with automatic reading function
• Bi-directional Meter (Single direction meter replaced with bi-directional meter)
Ideal Location• Near CLP Supply Point• Readily accessible by CLP’s staff for
regular check • No potential safety hazards
FiT Meter board
FiT Meter
Revenue Meter
CLP
Feed-in Tariff Scheme Metering Example
• Determine the amount of electricity generated by the RES
• To be installed inside an existing switch room or meter box ( or location agreed by CLP)
• Equipped with automatic reading function
• Communication for FiT meter will be supplied by CLP (Only applied to ≤ 60 Ampere (Single-Phase) or ≤ 100 Ampere (Three-Phase))
*Pre-
Meter
lockable
MCCB
* 2-P (1 Ø ) or 4-P (3-Ø ) Circuit Breaker /Isolation Switch
Information Classification: Proprietary
Feed-in Tariff Scheme – Metering Standard
Page 19
o Typical Outdoor Meter Box (Feed-In Tariff) (60A Single Phase or 100A Three Phase)
Information Classification: Proprietary
Summary
Page 20
o Power System Security
• To ensure power system security, application to utility
is required for RES with parallel design or change-
over design (using change-over device)
o Power Quality
• RES is a power source, due considerations are
required to ensure the power quality and reliability
requirements of electricity supply in Hong Kong in
addition to safety.
o Regulations
• The RES owner and REC/REW should ensure that
the RES complies with all prevailing statutory
requirements and best practices
Information Classification: ProprietaryInformation Classification: Proprietary
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